Evidence of Ancient Towns Found in Amazon Basin

"This research overlaps what we're finding in Bolivia in that it shows massive transformations of the landscape through agriculture, transportation, and controlling water, using some pretty sophisticated engineering techniques," he said.

The arrival of the Spanish and Portuguese around 1600 brought Old World diseases, slavery, missions, and resettlement, depopulating much of Amazonia within 100 years.

Myth of the Pristine Environment

The findings have implications for economic development of the Amazon today.

The Amazon is a notoriously hostile environment for agriculture. Some research indicates that fields may need to be left fallow for as long as ten to 30 years before they can be replanted, said Heckenberger.

"If that's the case, think of the enormous amount of space needed to maintain active production. It's hard to imagine there was much of the land that was big tracts of untouched forest," he said. "What forest there was, was there because they intentionally left it there. And it was a working forest, known to them, not some sort of primordial wilderness."

Some conservationists argue that much of the Amazon is pristine wilderness that would not survive encroachment by humans.

"Finding large scale population centers in such a remote region of the Amazon adds weight to the idea that there are no pristine patches of nature," said Erickson. "The extent and dating of the modifications [identified in the Heckenberger study] show that the impact of humans has been substantial, profound, and long-lasting."

"This shows it's not an all-or-nothing type of deal: Let's cut it all down or we can't let anybody in it because it's pristine and never been touched by human hands," said Heckenberger. "The Amerindians essentially transformed the entire forest landscape. But they did it in a sustainable, not destructive way."